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send data via uhf

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by elctrochania, Nov 14, 2005.

  1. elctrochania

    elctrochania New Member

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    hi i need help! i want to send data via a uhf voice tranciver(walkietolklie) with a low bitrate(i dont mind). so ineed some good ideas about that. i have a pair of uhf transceiver with a total bandwidth of 700khz and it is from 700khz to 1400khz. so i need to convert data to voice and then voice to data.plz help
     
  2. mstechca

    mstechca New Member

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    Why do you care?
    You can convert data to voice by ripping out the microphone on the transmitter, and replacing it with an astable multivibrator running at a few dozen hertz. The multivibrator promotes the data. When the multivibrator is not functioning, a binary 0 is sent.

    For voice to data, rip out the speaker in the receiver and replace it with the Stereo VU meter found at talkingelectronics.com.

    For best results, make sure the reveiver recognizes the speed of the transmitter (multivibrator frequency), or you will lose characters.
     
  3. elctrochania

    elctrochania New Member

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    thnx for that but my real problem is that i dont want to remove mic or speaker! i need to use it for sending data and voice and i dont want to recieve fake data if someone talks! So i need some kind of modulation or something! of course i dont want to send data and voice at the same time.
     
  4. dave

    Dave New Member

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  5. mstechca

    mstechca New Member

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    Why do you care?

    How can you send data with a speaker? are you going to runthe transmitter through a food procesor so that the receiver makes a continuous clicking sound? :lol: or are you going to consistently smash the transmitter until you hear something in the receiver? :lol:

    In other words, speaker should not be used as data input because it isn't reliable. It is better for voice input.


    Thats why I said rip out the microphone. The microphone is the thing someone talks into. The only other way your transmission is screwed is if a nearby transmitter is transmitting at the same frequency.

    use the transceivers you already have. the speaker accepts input, and modulates it to a higher frequency.

    then go with my above suggestion in my first reply.
     
  6. elctrochania

    elctrochania New Member

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    man here is paint about! i know its hard! but plz give a try! i need those 2 boxes (audio2data mod & data2audio demmod)!!!!!!!!!!! thats what i need and if i get those 2 boxes i ll have both data and voice com!!! and i dont mind if i have a beeep on speaker when i send data! thnx a lot!!!
     

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  7. stevez

    stevez Active Member

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    It sounds like you are describing a modem - modulator/demodulator. Sometime between the time that dinosaurs ceased to roam the earth and the present time, computers were linked to each other via a telephone modem. You put the handset in the modem's cradle on each end and the modem converted the datastream into audio (modulate) and then at the other end it converted the audio into a datastream (demodulate).

    With your transceivers you'd be limited to one way communication however you could use two pairs for two way communication.
     
  8. elctrochania

    elctrochania New Member

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    stevez:
    It sounds like you are describing a modem - modulator/demodulator

    me:
    thnx for info


    stevez:
    Sometime between the time that dinosaurs ceased to roam the earth and the present time, computers were linked to each other via a telephone modem. You put the handset in the modem's cradle on each end and the modem converted the datastream into audio (modulate) and then at the other end it converted the audio into a datastream (demodulate).

    me:
    if i want a historical review ill to find it in an ather place

    stevez:
    With your transceivers you'd be limited to one way communication however you could use two pairs for two way communication

    me:
    pls take a look at that photo is it or not HD 2way com??? IN ONE PAIR???

    IF SOMEONE HAVE A GOOD IDEA (electronic idea)ON HOW TO MAKE THOSE 2 BOXES (data to audio mod & audio 2 data dem) PLZ SHARE IT WITH ME!!!!!!
     

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  9. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It's only one way at a time, which means you have to control RX/TX switching as well, you might also consider the legal implications?, are you permittd to send data on the frequency in question? - most usually NOT!.

    I suggest you try googling for "packet radio modem", which is what radio amateurs use for data communications, on specific allocated legel frequencies.
     
  10. mstechca

    mstechca New Member

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    Why do you care?
    a microphone can be considered as a speaker, so your hand drawn diagram indicates to me that your microphone will function exactly the same as your speaker, because they are connected in series.

    You could also do full-duplexing which means two frequencies are required. one for sending, and the other for receiving. But some stations you connect to may not support it which in that case, use Nigel's idea.


    I searched for that myself. The best I got was a circuit for an interface between the computer and the radio (a.k.a. a ridiculously simple TNC)
     
  11. elctrochania

    elctrochania New Member

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    "It's only one way at a time"
    i know that "pls take a look at that photo is it or not HD 2way com"
    the HD=half dublex
    BUT I REALY THANK YOU FOR "packet radio modem"!!!!!!!!!
    THANK YOU SO MUCH I FOUND WHAT I WAS LOOKING FOR!!!!
    THANKS AGAIN!!!!!!! FOR MY NEXT QUESTION I'LL PM YOU FIRST!
     
  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    An electret mic can't be used as a dynamic speaker, but a dynamic (coil and magnet) mic can.

    They aren't in series. Both are connected to ground.
     
  13. bryan1

    bryan1 Well-Known Member

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    Like most of the answers msecha writes everyone needs to be corrected. Looks like he should get off the organic smokes and go back to school well pre-school should be a good start
     
  14. Mike - K8LH

    Mike - K8LH Well-Known Member

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    Many of us Ham Radio Operators were treated to a new digital mode invented by a gentleman in the UK several years ago called PSK31... It's very narrow bandwidth provides an excellent signal-to-noise ratio and many of us have acheived some very nice low power/weak signal contacts with it... Best of all, it utilizes the DSP capabilities of the sound card in your PC and connects easily from the sound card to the audio connectors on our transceivers... It also works quite well from PC to PC simply using speakers and mics' on both PCs (grin)...

    Try googling PSK31 and download one of the many free PSK31 programs...

    Have fun... Regards, Mike
     
  15. mstechca

    mstechca New Member

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    Why do you care?
    normally I don't answer completely wrong, but this time I did, because his ground symbol was not a standard one, and his circuit looked like he drew it in 10 seconds.

    When I was answering, I missed the ground symbol.
     
  16. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Hi MStechca,
    You're forgiven this time. :lol:
     

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